Radiator Size ????

While it is true that copper is more thermally conductive vs aluminum, air-to-water heat exchangers are dominated by the air side effectiveness, which the aluminum fin is much more effective than copper.

Factory Mopar thermostats flow significantly more than the aftermarket standard. I suspect the run of the mill "Stant" or typical units are a Chevy/Ford design. If you see an actual 2128944/3514774 or 3514177, the opening diameter is about 7/16' larger. Run a high flow or factory thermostat.